Treatment of textile fabric



June 10, 1969 R. SCHENC'K 3,449,060 7 TREATMENT OF TEXTILE FABRIC IFiled Nov. 4, 1963 I Sheet of 2 B -o x, 1 Q

ATTORNEYS United States Patent 3,449,060 TREATMENT OF TEXTILE FABRICJohn R. Schenck, Charlotte, N.C., assignor to Klopman Mills, Inc.,Ashehoro, N.C., a corporation of Delaware Filed Nov. 4, 1963, Ser. No.321,096 Int. Cl. D06m 1/02, 9/12, 9/04 US. Cl. 8125 4 Claims The presentinvention relates to a novel process and apparatus for continuouslycausticizing textile fabric. The invention is of particular significancein the treatment of woven fabric comprising blends of cotton andpolyester textile material but other types of fabrics which are normallysubjected to causticizing or mercerizing treatment may also be processedin the manner described herein.

Broadly stated, the invention involves successively impregnating thefabric with caustic soda solution and aerating the thus treated fabricafter each impregnation, the fabric being held under warp tensionthroughout the impregnation and aeration. Surprisingly, it has beenfound that this sequence of operations makes it possible to veryeffectively causticize the fabric continuously and in a minimum lengthof time with optimum results.

The exact reasons for the improved results of the invention are notunderstood. However, it appears that the caustic soda in the fabricloses some of its strength during the subsequent aeration step throughbeing converted to carbonate of soda by means of carbonic acid in theatmosphere. In any event, it is apparent that successive caustic sodatreatments followed in each case by aerating, all while the fabric isunder a constant amount of warp tension, create highly desirable effectson cotton/polyester blend fabrics and the like. These effects, bothchemical and physical, remain on the fabric after neutralizing andsubsequent steaming and/ or washing.

The treatment of the invention is uniquely different from conventionalcotton mercerizing or causticizing operations. In the past,mercerization has generally been carried out using so-called chain orexpander mercerizers. With the chain mercerizers, the fabric is heldunder extreme filling tension (e.g. tensions of the order of 25% of thefabric break strength) by clips or the like attached to chains which arepositioned along the edges of the fabric. Numerous problems areassociated with the use of these chain mercerizers. For one thing, thecaustic soda has an undesirable eifect on the chains. Furthermore, thesubstantial tension in the filling direction is undesirable and it isdifficult to insure width uniformity. Expander mercerizers also applyconsiderable filling tension on the fabric and suffer from lack of widthuniformity and other disadvantages. Hence, it will be appreciated thatthere is considerable room in this highly developed field forimprovements which will obviate the disadvantages encountered in priorprocedures.

In contrast to the techniques conventionally employed in the past, thepresent invention eliminates the use of chains and requires only warp(lengthwise) tension during the caustic soda impregnations and aeratingsteps, with minimal fillingwise tension, suflicient only to keep thefabric free from creases (i.e. tension not in excess of -20 poundsoutward thrust).

The various features of the present invention are more fully describedbelow in conjunction with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic view of part of the system contemplatedherein for successively impregnating the fabric with caustic sodasolution followed by aeration;

FIGURE 2 is a diagrammatic view of the balance of the system shown inFIGURE 1; and

FIGURES 3 and 4 are top views of the system shown in FIGURES 1 and 2,respectively.

Referring now more specifically to the system shown 3,449,060 PatentedJune 10, 196

in the accompanying drawings, fabric F which has been previously bonedried (i.e. dried to a moisture content below 5%, by means not shown) isfed to a first causticizing pan or tube 10 appropriately mounted on ametal supporting frame 11. Tub 10 may be made of mild steel or the likeand is adapted to contain caustic soda solution supplied through anappropriate supply 12. The temperature and concentration of the solutionin tub 10 and the other tubs hereinafter referred to can be widelyvaried but, generally speaking, the temperature of these solutions willbe in the range of to F. and the caustic concentration will be about2025% by weight. Usually, the same temperature and concentration areused throughout the process although these can be varied as desired.

Within tub 10 there is provided a bottom horizontal row of rolls 13positioned so that they are normally immersed in the caustic solution.Additionally, there is a top row of rolls 14 mounted on frame 11 so asto be either partially immersed in the liquid in tub 10 or just abovethe same. 7

As shown, the fabric F is alternatively passed over a top roll 14 andunder a bottom roll 13 through tube 10 and then over a gently curvedroller 16 (see especially FIGURE 3) which exerts just sufficientfillingwise tension to keep the fabric flat. From the roller 16, thefabric passes nip rollers 18 which are positioned just beyond roller 16.Liquid tapeup as a result of the caustic treatment in tank 10 willusually amount to from to by weight, based on the weight of dry fabricand the nip rollers 18 reduce the liquid content to 95 to 100% byweight. From these rollers 18, the fabric is passed under a guide roll19 and then over another gently curved roller 20 which again serves tosimply smooth out the fabric in the filling direction.

From the roller 20, the fabric is passed through the first aerating zonewhich comprises a plurality of rotatable cylinders or cans 22 mounted,as shown, on a vertical frame 24. As shown, this first aerating zoneincludes two vertical rows of six cans each with two intermediatehorizontally disposed cans joining the top of the two rows. However, itwill be recognized that more or less than this number of cans can beused, depending on the can size, to provide the necessary aerating time.Advantageously, cans 22 are conventional drying cans although, in thepresent case, the cans are not heated but simply serve to provide thenecessary time for aerating the caustic treated fabric prior to the nextimmersion step. The aeration time may be varied but, generally speaking,will usually 1 fall in the range of .13 to .23'minute from the exit ofone immersion pan to the entrance of the next pan.

The fabric leaving the last can 22 is then fed through a second pan ortub 25 of mild steel or the like containing caustic as in the case oftub 10. The fabric is passed through tub 25 by means of top rolls 26 andbottom rolls 2-8 in the same manner as the first caustic treating tub 10although tub 25 is desirably shorter in length than tub 10 so that thecaustic treatment in tub 25 is shorter in time (e.g. about half) thanthe time for the first treatment. This is also preferably the case withrespect to the canstic treatment following tub; 25.

After the caustic treatment in tub 25, the fabric is passed through aseries of curved expanders 30 suitably mounted on frame 11 and arrangedas shown in FIGURE 1. These expanders may be driven by appropriatemeans, e.g. a right angle gear motor 31 as diagrammatically shown inFIGURE 3. Similar means may also be provided for driving the other rollsused herein as may be necessary. The expanders 30 continue to maintainthe fabric in the fiat condition with minimum fillingwise tensionthereon. The warp tension on the fabric is maintained by means of theother rolls, e.g. the various sets of nip rolls with appropriatecompensating means to maintain this tension constant throughout.

Following the expanders 30, the smooth fabric is fed through anotherpair of adjustable nip rollers 32, under a guide roll 34, over anothercurved roll 36 and then into the second aerating zone comprising thetiming cylinders or cans 37 arranged as shown in FIGURE 1 on a frame 38and operating in the same manner as cans 22.

From this second series of cans 37, the fabric is again treated withcaustic in the tub 39 in the manner previously described. As before, pan39 includes the top and bottom rolls 40 and 41, respectively, and fromthe last roll 40, the fabric is fed over the curved eX-panders 42,through nip rolls 44, under guide roll 45, over the curved roll 46 andthen through another series of aerating cans 48 after which the fabricis fed into a washing pan 50 filled with wash water by means not shown.From this initial wash, the fabric is passed through another series ofexpanders 52 to be sure the fabric is crease-free and then through niprolls 54, all as in the manner heretofore described. It will be notedthat the further caustic treatment in tub 39 and the water Wash in tub50 are again only about one half as long as the treatment in the initialtub so that, in the embodiment shown, the total time of immersion incaustic in tubs 25 and 39 is equal to the time of the caustic treatmentin the first tub 10.

As shown in FIGURE 1, angularly disposed trays 56 are provided betweentubs 10, 25, 39 and 50* in a position to collect caustic which isremoved by the nip rolls or otherwise comes off the fabric at any othertime during passage between tubs. These trays are appropriately shapedas shown to direct the collected caustic back into the top of thepreceding tub or the following one.

As noted earlier, caustic is fed to the tubs by means of conduit 12, thelatter being supplied with caustic solution through an inlet 58.Appropriate valve means 59 are provided in the conduit, as necessary, tocontrol the amount supplied to each tub.

A pan or the like designated at 60, is also provided for returningcaustic from nip rolls 54 to the preliminary wash tub 50.

As shown in FIGURE 2, the fabric is passed from nip rolls 54 upwardly toa feed roll 62 and then downwardly into a combination steam and washerunit or caustic recuperator 64, where the fabric is alternately treatedwith steam and water flowing in a direction opposite to the fabricdirection. Steam is sprayed into the unit at points 66 positionedbetween alternate passes of the fabric intermediate top rolls 68 andbottom rolls 70, the top rolls being driven. Steam at .1 to .2 p.s.i.g.is usually suflicient for this purpose and relief means 72 may besupplied to prevent pressure above a desired limit, e.g. 4 p.s.i.g. Avacuum breaker 74 may also be advantageously included in the system.

To provide the desired countercurrent flow of water, the water is fedinto the unit 64 at the fabric outlet end and allowed to cascadedownwardly as shown to the fabric entrance end of the unit where thewater is withdrawn by appropriate means (not shown). The withdrawn watercontains the caustic removed from the fabric and, if desired, may berecycled to one of the caustic tubs.

From the steam and washer unit 64, the fabric is drawn over a guide roll76, the curved roll 77 to keep the fabric fiat and nip rolls 78 and thenfed by way of rolls 79 and 80 into the first of a series of wash tanks81 containing water at an essentially constant level as shown at 82.Wash tank 81 may be suitably mounted on a metal supporting frame 83 andincludes the lower set of rolls 84 immersed in the wash water. Upperrolls 86 are mounted on frame 83 and the fabric is passed back and forthbetween rolls 84 and 86 through tank 81. The thus washed cloth is fedover another curved fabric flattening roll 88 and then through the niprolls 90, water removed by the rolls 90 being fed back into the vessel81 by means of an appropriate drip plate 92. Washing of the fabric isthen repeated several more times as indicated (five additional timesbeing shown) using a wash system as just described. For convenience, thesame numerals are used to identify the various elements of the furtherwashing operations.

It is to be noted that the fabric leaving the wash nip rolls passesunder a roll 93 and then upwardly around a roll 94 before going into thenext washing operation (or other treatment in the case of the lastwashing operation). Roll 93 may be used as a compensator toappropriately adjust the warp tension on the fabric if this is needed.

The fabric leaving the last pair of nip rolls 90 after the final wash ischaracterized by highly desirable physical and chemical properties as aresult of the successive 'causticizing and aerating operations describedabove. If desired, the fabric may be taken from the last series of rollsand fed continuously into appropriate drying means and/or otheroperations, e.g. scutching and finishing. The present system, by virtueof the sequence of operations described herein lends itself tocontinuous operations for treating fabric from, for example, bleachingthrough drying, causticizing as described herein and finishing.

The present process and apparatus are especially useful in the treatmentof woven fabric comprising polyester/ cotton blends. Such fabric maycomprise such blends in both warp and filling or, if desired, the blendsmay be used only in the filling or warp with polyester or cotton in theother direction. Typical staple blends comprise 3565% polyester and 6535cotton although other proportions may also be used. The polyestercomponent may be conventional polyethylene terephthalate such as theproducts known as Dacron, Terylene, Fortrel or the like. Othercellulosic materials which may be suitably processed in the mannerdescribed herein are the spun rayons of the viscose and cuprammoniumtypes, including the more recent high wet modulus rayons such as Moyneland Avril and the crosslinked rayon Corval.

Warp tension on the fabric processed in the manner described herein willusually fall in the range of 30 to 50 pounds. This tension is obtainedby means of the various rolls used with whatever adjustment of thecompensator means may be needed as the operation proceeds to keep thetension essentially constant throughout. Of the rolls referred to above,the driven rolls include all of the top rolls 14, 26 and 40 associatedwith the tubs 10, 25 and 39, respectively; the top rolls for the washtub 50, steam and washer unit 64 and the several washing tanks 81; theseveral curved fabric straightening rollers; the top roll for each pairof nip rolls; and the various cans forming the several aerating zones.

The invention is illustrated further by reference to the followingoperating conditions using the system shown in the drawings for thetreatment of a woven fabric comprising, per inch, 80 to warp ends of 65%polyester and 35% cotton blends and 40 to 90 filling ends of 65polyester and 35 cotton blends:

Caustic concentration Tub 10 percent by weight 20 Tub 25 do 20 Tub 39 do20 Time of impregnation Tub 10 minutes .10 to .17 Tub 25 do .06 to .10Tub 39 do .06 to .10

Aerating time From tub 10 to tub 25 "minutes" .13 to .23 From tub 25 totub 30 do .13 to .23 From tub 39 to tub 50 do .13 to .23 Total aeratingtime do .39 to .69 Warp tension, total pounds 30 to 50 Filling tension(Only sufficient to avoid creases). Total treatment time (From entranceto first tub through finalwash) "minutes" 1.50 to 2.60

It will be recognized that various modifications may be made in theinvention as described above without deviating from the scopethereof asset forth in the following claims.

I claim:

1. A continuous process for causticizing a textile fabric containingcellulosic-linear polyester blends which comprises impregnating thefabric with aqueous caustic soda solution at a temperature between 100and 110 F., a plurality of times, and aerating the thus treated fabricafter each said impregnation for .13 to .23 minute, maintaining saidfabric under lengthwise tension throughout said impregnating andaerating steps with minimal widthwise tension suflicient only to keepthe fabric smooth and wherein said fabric is washed, steamed and driedafter said impregnating and aerating steps, all of said operations beingcarried out continuously.

2. The process of claim 1 wherein the fabric is completely dry prior tothe first impregnating step.

Voegeli 8-125 Voegeli 8125 Bosshard 8125 Thies 8125 Nitsche 8125 Weiss8125 r NORMAN G. TORCHIN, Primary Examiner. J. CANNON, AssistantExaminer.

U.S. Cl. X.R.

1. A CONTINUOUS PROCESS FOR CAUSTICIZING A TEXTILE FABRIC CONTAININGCELLULOSIC-LINEAR POLYESTER BLENDS WHICH COMPRISES IMPREGNATING THEFABRIC WITH AQUEOUS CAUSTIC SODA SOLUTION AT A TEMPERATURE BETWEEN 100*AND 110*F., A PLURALITY OF TIMES, AND AERATING THE THUS TREATED FABRICAFTER EACH SAID IMPREGNATION FOR .13 TO .23 MINUTE, MAINTAINING SAIDFABRIC UNDER LENGTHWISE TENSION THROUGHOUT SAID IMPREGNATING ANDAERATING STEPS WITH MINIMAL WIDTHWISE TENSION SUFFICIENT ONLY TO KEEPTHE FABRIC SMOOTH AND WHEREIN SAID FABRIC IS WASHED, STEAMED AND DRIEDAFTER SAID IMPREGNATING AND AERATING STEPS, ALL OF SAID OPERATIONS BEINGCARRIED OUT CONTINUOUSLY.